Fuel pumping system and method

ABSTRACT

A fuel pumping system that includes a pump drive is provided. A first pumping element is operatively connected to the pump drive and is operable to generate a first flow of pressurized fuel. A second pumping element is operatively connected to the pump drive and is operable to generate a second flow of pressurized fuel. A first solenoid is operatively connected to the first pumping element and is operable to vary at least one of a fuel pressure and a fuel flow rate of the first flow of pressurized fuel. A second solenoid is operatively connected to the second pumping element and is operable to vary at least one of a fuel pressure and a fuel flow rate of the second flow of pressurized fuel.

U.S. GOVERNMENT RIGHTS

This invention was made with government support under the terms ofContract No. DE-FC05-00OR22806 awarded by the Department of Energy. Thegovernment may have certain rights in this invention.

TECHNICAL FIELD

The present invention is directed to a fuel system and, moreparticularly, to a fuel pumping system and method.

BACKGROUND

The operation of an internal combustion engine such as, for example, adiesel, gasoline, or natural gas engine, may cause the generation ofundesirable emissions. These emissions, which may include particulatesand oxides of nitrogen (NOx), are generated when fuel is combusted in acombustion chamber of the engine. An exhaust stroke of an engine pistonforces exhaust gas, which may include these emissions, from the engine.If no emission reduction measures are in place, these undesirableemissions will eventually be exhausted to the environment.

Research is currently being directed towards decreasing the amount ofundesirable emissions that are exhausted to the environment during theoperation of an engine. It is expected that improved engine design andimproved control over engine operation may lead to a reduction in thegeneration of undesirable emissions. Many different approaches such as,for example, exhaust after-treatments, have been found to reduce theamount of emissions generated during the operation of an engine. The useof exhaust aftertreatments requires periodic regeneration of theaftertreatment systems. Aftertreatment regeneration may requireincremental fueling in the form of late post injections, which requireadditional capacity of the fuel delivery system.

Another method of reducing undesirable emissions involves improving thecombustion characteristics of the engine. This may be accomplished, forexample, by implementing homogeneous charge compression ignition (HCCI)in the engine. In a HCCI engine, fuel enters the engine with the intakeair prior to or at the start of the compression stroke and both theintake air and fuel are heated in the compression stroke. HCCI operationrequires precise control over fuel flow and fuel delivery pressure. Forexample, HCCI may require early fuel injection timing and a reduced fuelinjection pressure that limits spray penetration during the associatedrelatively low cylinder air densities.

The fuel flows and pressures required to efficiently run low emissionengines utilizing after-treatment solutions and/or HCCI may varygreatly. In order to ensure that a sufficient supply of fuel at asufficient pressure is always available to fulfill the demands of theengine, the fuel delivery system should be capable of supplying thelargest anticipated quantity of fuel at the highest anticipated pressurethat could be demanded. Unfortunately, this design approach typicallyresults in a fuel system that is over designed for typical engineoperation and may, therefore, be inefficient for the majority of theengine's operation.

As described in U.S. Pat. No. 6,253,735 to Miyajima et al., issued onJul. 3, 2001, a fuel system may include multiple, selectively actuatedfuel pumps that are operable to deliver an increased fuel flow rate whendemanded. When the demand for fuel is low, one of the fuel pumps may bedeactivated, thereby reducing the load on the engine and increasingengine efficiency. However, the fuel system described in the '735 patentto Miyajima et al., which includes multiple pumps, regulators, valvingarrangements, and controllers, may be overly complex and costly.

The fuel pumping system of the present invention solves one or more ofthe problems set forth above.

SUMMARY OF THE INVENTION

One aspect of the present disclosure is directed to a fuel pumpingsystem that includes a pump drive. A first pumping element isoperatively connected to the pump drive and is operable to generate afirst flow of pressurized fuel. A second pumping element is operativelyconnected to the pump drive and is operable to generate a second flow ofpressurized fuel. A first solenoid is operatively connected to the firstpumping element and is operable to vary at least one of a fuel pressureand a fuel flow rate of the first flow of pressurized fuel. A secondsolenoid is operatively connected to the second pumping element and isoperable to vary at least one of a fuel pressure and a fuel flow rate ofthe second flow of pressurized fuel.

Another aspect of the present disclosure is directed to a method ofcontrolling a fuel system. A first pumping element is operated toproduce a first flow of pressurized fuel. A second pumping element isoperated to produce a second flow of pressurized fuel. A first solenoidis selectively energized to vary at least one of a fuel pressure and afuel flow rate of the first flow of pressurized fuel. A second solenoidis selectively energized to vary at least one of a fuel pressure and afuel flow rate of the second flow of pressurized fuel. The first andsecond flows of pressurized fuel are directed to a fuel injection systemassociated with a combustion chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and diagrammatic illustration of an exemplaryembodiment of an internal combustion engine having a fuel pumping systemin accordance with the present disclosure;

FIG. 2 is a schematic and diagrammatic illustration of a first exemplaryembodiment of a fuel pumping system in accordance with the presentdisclosure;

FIG. 3 is a schematic and diagrammatic illustration of a secondexemplary embodiment of a fuel pumping system in accordance with thisdisclosure; and

FIG. 4 is a schematic and diagrammatic illustration of a third exemplaryembodiment of a fuel pumping system in accordance with the presentdisclosure.

DETAILED DESCRIPTION

An exemplary embodiment of an engine 10 is illustrated in FIG. 1. Forthe purposes of this disclosure, engine 10 is depicted and described asa four-stroke diesel engine. One skilled in the art will recognize,however, that engine 10 may be any other type of internal combustionengine such as, for example, a gasoline or natural gas engine.

As illustrated in FIG. 1, engine 10 includes an engine block 12 thatdefines a plurality of cylinders 14. A piston 15 is slidably disposedwithin each cylinder 14. Engine 10 may also include a cylinder head 16associated with each cylinder 14.

Cylinder 14, piston 15, and cylinder head 16 form a combustion chamber17. In the illustrated embodiment, engine 10 includes six combustionchambers 17. One skilled in the art will readily recognize that engine10 may include a greater or lesser number of combustion chambers 17 andthat combustion chambers 17 may be disposed in an “in-line”configuration, a “V” configuration, or any other conventionalconfiguration.

As also shown in FIG. 1, engine 10 includes a crankshaft 18 that isrotatably disposed within engine block 12. A connecting rod 20 connectseach piston 15 to crankshaft 18. Each piston 15 is coupled to crankshaft18 so that a sliding motion of piston 15 within the respective cylinder14 results in a rotation of crankshaft 18. Similarly, a rotation ofcrankshaft 18 will result in a sliding motion of piston 15.

Engine 10 may also include a fuel injection system 23 having a series offuel injection units 24 disposed within each cylinder head 16 andassociated with combustion chambers 17. Each fuel injection unit 24 isoperable to inject an amount of pressurized fuel into combustion chamber17 at predetermined fuel pressures and fuel flow rates. Each fuelinjection unit 24 may be mechanically, electrically, or hydraulicallyoperated.

The timing of fuel injection into combustion chamber 17 may besynchronized with the motion of piston 15. For example, fuel may beinjected as the piston 15 nears a top-dead-center position in acompression stroke to allow for compression-ignited-combustion of theinjected fuel. Alternatively, fuel may be injected as the piston 15begins the compression stroke heading towards a top-dead-center positionfor homogenous charge compression ignition operation. Fuel may also beinjected as the piston 15 is moving from a top-dead-center positiontowards a bottom-dead-center position during an expansion stroke for alate post injection to create a reducing atmosphere for aftertreatmentregeneration.

As shown in FIG. 1, a fuel pumping system 26 may be operably connectedto the engine 10 and driven by the crankshaft 18. The fuel pumpingsystem 26 may be connected with crankshaft 18 in any manner readilyapparent to one skilled in the art where a rotation of crankshaft 18will result in a corresponding rotation of a pump drive shaft 58. Forexample, fuel pumping system 26 may be connected to crankshaft 18through a gear train 59.

The fuel pumping system 26 may be adapted to draw fuel from a supply 28.Fuel pumping system 26 may be adapted to increase the pressure of thefuel and direct one or more pressurized streams of fuel to fuelinjection system 23. A fuel transfer pump 34 may be disposed in a fuelline 36 between the supply 28 and the fuel pumping system 26 andconfigured to provide low pressure feed to fuel pumping system 26.

Fuel pumping system 26 may include a first pumping element 40 operablyconnected to pump drive shaft 58 and a second pumping element 42operably connected to pump drive shaft 58. In the embodiment of FIG. 1,first pumping element 40 is disposed in a first pump housing 41 andsecond pumping element 42 is disposed in a second pump housing 43.Alternatively, first and second pumping elements 40, 42 may be disposedwithin the same pump housing.

Each of the first and second pumping elements 40, 42 may be adapted togenerate a flow of pressurized fuel. For example, the first pumpingelement 40 may generate a first flow of pressurized fuel and the secondpumping element 42 may generate a second flow of pressurized fuel. Eachof the first and second pumping elements 40, 42 may be any type ofpumping element such as, for example, an in-line piston pump having aseries of pistons 39.

Each of the first and second pumping elements 40, 42 may include acontrol element that is adapted to vary at least one of a flow rate anda pressure of the respective flow of pressurized fuel. For example, eachof the first and second pumping elements 40, 42 may be a hydraulicallyactuated, electronically controlled unit injector pump. First and secondpumping elements 40, 42 may include a rotatable cam (not shown) adaptedto drive the series of in-line pistons through a compression stroke topressurize fuel. A plunger (not shown) may be closed at variable timingsto change the length of the compression stroke and thereby vary the flowrate of the pumping element. Alternately, first and second pumpingelements 40, 42 may include a rotatable swashplate, or any other meansknown in the art for varying the flow rate of pressurized fuel.

An actuating device, such as a solenoid, may be connected to eachpumping element to govern the position of the control element to therebycontrol at least one of the flow rate and the flow pressure of therespective pumping element. A first solenoid 44 may be connected to thecontrol element of the first pumping element 40 to cause it to produce afirst fuel stream in response to a demand for a particular fuel pressureand/or a fuel flow rate. Likewise, a second solenoid 45 may be connectedto the control element of the second pumping element 42 to cause it toproduce a second fuel stream in response to a demand for a fuel pressureand/or a fuel flow rate. Fuel pumping system 26 may be operable toproduce a range of fuel flow rates at a range of fuel pressures byselectively operating the first solenoid 44 and the second solenoid 45to control the position of the respective control element and byselectively directing the pressurized fuel along various fuel paths, aswill be described in greater detail below.

The fuel pumping system 26 may include a controller 46, adapted tocontrol the first and second solenoids 44, 45. Controller 46 may includeall the components required to run an application such as, for example,a memory, a secondary storage device, and a processor, such as a centralprocessing unit. One skilled in the art will appreciate that thecontroller 46 can contain additional or different components.Furthermore, although aspects of the present disclosure may be describedas being stored in memory, one skilled in the art will appreciate thatthese aspects can also be stored on or read from other types of computerprogram products or computer-readable media, such as computer chips andsecondary storage devices, including hard disks, floppy disks, CD-ROM,or other forms of RAM or ROM. Associated with the controller 46 may bevarious other known circuits such as, for example, power supplycircuitry, signal conditioning circuitry, and solenoid driver circuitry,among others.

Controller 46 may selectively control the first solenoid 44 and thesecond solenoid 45 to change the pressure and/or flow rate of each ofthe first and second flows of pressurized fuel in response to changingdemands for fuel flow rate and fuel pressure. For example, controller 46may control first and second solenoids 44, 45 to increase flow rates ofthe first flow and decrease flow rates of the second flow in response toHCCI operation of the engine 10 that requires reduced injectionpressure. Controller 46 may energize second solenoid 45 to therebyincrease the second flow rate for normal operation of the engine 10 thatrequires a higher fuel pressure. Alternatively, controller 46 maycontrol first and second solenoids 44, 45 to increase flow rates of thefirst flow and decrease flow rates of the second flow for use duringnormal operation and energize second solenoid 45 to thereby increase thesecond flow rate for use during aftertreatment regeneration whichrequires incremental fueling in the form of late post injections tocreate a reducing atmosphere (oxygen-limited). Controller 46 may alsoselectively energize the first and second solenoids 44, 45 in responseto a change in loading conditions of the engine 10.

As illustrated in FIGS. 1 and 2, the first and second pumping elements40, 42 may be connected to a manifold 32 by way of fuel lines 30 and 31respectively. Check valves 33 and 35 may be disposed within fuel lines30 and 32 respectively. Manifold 32 may be connected to fuel injectionunits 24 by way of a plurality of fuel lines 38. In this manner, firstand second pumping elements 40, 42 may be configured to operate inparallel, each drawing fuel from the same supply 28 and directing eachrespective pressurized flow of fuel to the same manifold 32.

In the embodiment of FIG. 2, first pumping element 40 may be operated toproduce a first flow of pressurized fuel at a first flow rate and afirst pressure, which may create a first spray plume pattern 54 whenfuel injection unit 24 is actuated to inject a quantity of fuel from themanifold 32 into the combustion chamber 17. Additionally, second pumpingelement 42 may be simultaneously operated to produce a second fuelstream at a second flow rate depicted as spray plume 56. The first andsecond fuel streams may be combined in the manifold 32, therebyincreasing the total fuel flow rate and/or pressure to create a secondspray plume pattern 57 when fuel injection unit 24 is actuated.

As shown in FIG. 3, fuel injection system 23 may include multiple fuelmanifolds that supply fuel to a fuel injection unit 64. A first manifold50 may be connected to fuel injection unit 64 through a plurality offuel lines 60. A second manifold 52 may be connected to fuel injectionunit 64 through a plurality of fuel lines 62.

Controller 46 may energize first solenoid 44 to actuate first pumpingelement 40 to produce a first stream at a first flow rate and a firstpressure. The first stream may be directed to first manifold 50 by wayof a fuel line 47. Controller 46 may energize second solenoid 45 toactuate second pumping element 42 to produce a second fuel stream at asecond flow rate and a second pressure. The second stream may bedirected to second manifold 52 by way of a fuel line 48.

The fuel injection unit 64 may be adapted to simultaneously receive thefirst and second streams of fuel. Fuel injection unit 64 may be operatedto inject the fuel from one of the first and second manifolds or both ofthe first and second manifolds 50, 52. In this manner, fuel injectionunit 64 may selectively create a first spray plume pattern 54, a secondspray plume pattern 56, and a third spray plume pattern 57 including thefirst and second spray plume patterns 54, 56 combined.

In the embodiment of FIG. 4, fuel injection system 23 may include afirst fuel injection unit 66 and a second fuel injection unit 68associated with each combustion chamber 17 (referring to FIG. 1). Firstfuel injection unit 66 may be operable to inject fuel into combustionchamber 17 (referring to FIG. 1) having a first flow rate and a firstinjection pressure. Second fuel injection unit 68 may be operable toinject fuel into combustion chamber 17 (referring to FIG. 1) having asecond fuel flow rate and a second injection pressure.

Controller 46 may energize first solenoid 44 to actuate first pumpingelement 40 and second solenoid 45 to actuate second pumping element 42to produce the first and second fuel streams directed to first andsecond manifolds 50 and 52, of the fuel injection system 23, asdescribed above. In the embodiment of FIG. 4, first manifold 50 isconnected to first fuel injection unit 66 by way of fuel lines 60 andsecond manifold 52 is connected to second fuel injection unit 68 by wayof fuel lines 62.

First fuel injection unit 66 may be selectively actuated to inject thefirst fuel stream to produce a first spray plume pattern 54. Second fuelinjection unit 68 may be selectively actuated to inject the second fuelstream to produce a second spray plume pattern 56. The first fuelinjection unit 66 and second fuel injection unit 68 may simultaneouslyinject the first and second fuel streams, producing the first and secondspray plume patterns 54, 56.

INDUSTRIAL APPLICABILITY

The operation of engine 10 will cause a rotation of crankshaft 18, andcorresponding rotation of pump drive shaft 58 that may cause anassociated pumping action of first pumping element 40 and second pumpingelement 42. Controller 46 may energize first solenoid 44 to cause firstsolenoid 44 to actuate first pumping element 40 to produce a first fuelstream having a first flow rate at a first pressure.

Referring to the embodiment of FIGS. 1 and 2, the first fuel stream maybe directed to fuel injection system 23 through a fuel line 30 to amanifold 32 and distributed to fuel injection units 24 through fuellines 38. Fuel injection units 24 may inject the first fuel stream toproduce a first fuel injection spray plume pattern 54 used forconventional combustion ignition operation of the engine 10.

As demand for fuel flow rate or pressure increases, such as duringaftertreatment regeneration, controller 46 may energize second solenoid45 to actuate second pumping element 42 to produce a second fuel streamhaving a second flow rate. This second fuel stream may be directed tofuel injection system 23 to join the first fuel stream supplied to fuelinjection units 24. The combined fuel streams may increase the fuel flowrate and to produce a second injection spray plume pattern 57 when fuelinjection unit 24 is actuated.

Operating the second pumping element only during times of increased fueldemand reduces the parasitic losses of the engine 10 during normaloperation. This reduction in parasitic losses may improve the overallefficiency of the engine 10.

Referring to FIG. 3, the fuel pumping system 26 may also be used tosimultaneously produce two streams of fuel having independent flow ratesand pressures that are independently delivered to fuel injection units64 of fuel injection system 23. Fuel pumping system 26 may cause firstsolenoid 44 to actuate first pumping element 40 to produce a first fuelstream having a first flow rate at a first pressure. This first fuelstream may be directed to fuel injection system 23 through a fuel line47 to a manifold 50 and distributed to fuel injection units 64 throughfuel lines 60. Fuel injection units 64 may inject the first fuel streamto produce a first fuel injection spray plume pattern 54 used for engineoperation requiring low fuel flow rates and pressures such as, forexample, homogeneous charge compression ignition.

As demand for fuel flow or pressure increases, fuel pumping system 26may cause second solenoid 45 to actuate second pumping element 42 toproduce a second fuel stream having a second flow rate at a secondpressure. This second fuel stream may be directed through a fuel line 48to a manifold 52 and distributed to fuel injection units 64 through fuellines 62. Fuel injection units 64 may selectively inject the second fuelstream to produce a second injection spray plume pattern 56. Fuelinjection units 64 may also simultaneously inject the first fuel streamand the second fuel stream to produce a third spray plume pattern 57.First, second, and third spray plume patterns 54, 56, 57 may also beused simultaneously and/or sequentially for conventional combustionand/or mixed mode combustion (i.e., homogeneous charge combustion andconventional combustion).

Referring to FIG. 4, the two streams of fuel from manifolds 50 and 52,described above, may be directed to two different sets of fuel injectionunits 66 and 68. Fuel injection units 66 and 68 may be selectively,sequentially, and/or simultaneously operated to produce variableinjection spray plume patterns similar to the first and second sprayplume patterns 54, 56 produced by fuel injection units 64 as describedabove.

The architecture of FIGS. 3 and 4 allow simultaneous provision ofoptimized fuel injection pressures for conventional combustion,homogeneous charge combustion, and/or mixed mode combustion processes.

The fuel system of the present disclosure has wide applications in avariety of engine types including, for example, diesel engines, gasolineengines, and natural gas engines. The disclosed invention may beimplemented into any engine that utilizes a pressurizing fuel system.The described system may decrease engine exhaust emissions by providinga range of fuel flow rates at a range of pressures as demanded byvarious emission compliant engine operating cycles. The disclosed systemmay also increase the overall efficiency of the engine by only actuatingthe pumping means necessary to meet the immediate needs of the engine.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the fuel injection controlsystem of the present disclosure without departing from the scope of thedisclosure. Other embodiments will be apparent to those skilled in theart from consideration of the specification and practice of the systemdisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope of the invention beingindicated by the following claims and their equivalents.

1. A fuel pumping system, comprising: a pump drive; a first pumpingelement operatively connected to the pump drive and operable to generatea first flow of pressurized fuel; a second pumping element operativelyconnected to the pump drive and operable to generate a second flow ofpressurized fuel; a first solenoid operatively connected to the firstpumping element and operable to vary at least one of a fuel pressure anda fuel flow rate of the first flow of pressurized fuel; and a secondsolenoid operatively connected to the second pumping element andoperable to vary at least one of a fuel pressure and a fuel flow rate ofthe second flow of pressurized fuel.
 2. The fuel pumping system of claim1, further including a controller operable to control the first andsecond solenoids to vary at least one of the fuel pressure and fuel flowrate of the first and second flows of pressurized fuel.
 3. The fuelpumping element of claim 1, wherein each of the first and second pumpingelements includes a series of pistons.
 4. The fuel pumping system ofclaim 1, further including a common manifold, and wherein the first andsecond pumping elements are connected to the common manifold inparallel.
 5. The fuel pumping system of claim 1, further including: afirst manifold in fluid communication with the first pumping element;and a second manifold in fluid communication with the second pumpingelement.
 6. A method of controlling a fuel system, comprising: operatinga first pumping element to produce a first flow of pressurized fuel;operating a second pumping element to produce a second flow ofpressurized fuel; selectively energizing a first solenoid to vary atleast one of a fuel pressure and a fuel flow rate of the first flow ofpressurized fuel; selectively energizing a second solenoid to vary atleast one of a fuel pressure and a fuel flow rate of the second flow ofpressurized fuel; and directing the first and second flows ofpressurized fuel to a fuel injection system associated with a combustionchamber.
 7. The method of claim 6, further including combining the firstand second flows of pressurized fuel for injection into the combustionchamber.
 8. (canceled)
 9. (canceled)
 10. (canceled)
 11. (canceled) 12.(canceled)
 13. (canceled)
 14. An engine system, comprising: an engineblock defining at least one combustion chamber; a pump drive; a firstpumping element operatively connected to the pump drive and operable toproduce a first flow of pressurized fuel; a second pumping elementoperatively connected to the pump drive and operable to produce a secondflow of pressurized fuel; a first solenoid operatively connected to thefirst pumping element and operable to vary at least one of a fuelpressure and a fuel flow rate of the first flow of pressurized fuel; asecond solenoid operatively connected to the second pumping element andoperable to vary at least one of a fuel pressure and a fuel flow rate ofthe second flow of pressurized fuel; and a fuel injection systemoperable to selectively inject the first and second flows of pressurizedfuel into the at least one combustion chamber.
 15. The engine system ofclaim 14, wherein each of the first and second pumping elements includea series of pistons.
 16. The engine system of claim 14, furtherincluding a common manifold in fluid communication with the fuelinjection system and wherein the first and second pumping elements areconnected to the common manifold in parallel.
 17. The engine system ofclaim 14, wherein the fuel injection system includes a fuel injectionunit adapted to selectively inject one of the first and second flows ofpressurized fuel into the at least one combustion chamber. 18.(canceled)
 19. (canceled)
 20. The engine system of claim 14, wherein thefirst and second pumping elements are disposed in first and secondpumping housings, respectively.